A method for altering the molecular weight of organosilicon compositions containing Si-bonded oxygen in the presence of phosphonitrile chloride catalysts is described in U.S. Pat. No. 3,839,388 to Nitzsche et al. In the method described in the above cited patent, a twin screw kneader, such as described in British Pat. No. 1,174,219 (Werner & Pfleiderer), is used as a reactor. Also, U.S. Pat. No. 4,128,568 to Buchner et al describes a continuous process for preparing highly viscous polydiorganosiloxanes, in which substantially cyclic diorganopolysiloxanes are reacted with chain-regulating materials in the presence of alkali catalysts. In the process described therein, the reactor consists of several zones, each of which is provided with stirring or transporting elements which generate countercurrents in two adjacent zones of the reactor.
Therefore, it is an object of the present invention to provide a continuous method for altering the molecular weight of organosilicon compositions containing Si-bonded oxygen without the formation of foam in the reactor. Another object of the present invention is to increase the capacity of the reactor without increasing the size of the reactor. A further object of the present invention is to provide a continuous method for altering the molecular weight of organosilicon compositions having Si-bonded hydrogen and achieve a better space-time-yield ratio.